The invention relates to the transmission of commands or data between elements of a home-automation installation for the attention of self-powered elements. The elements intercommunicate for example by radio-frequencies. They can in particular comprise actuators, sensors and control points.
Actuators are in general powered on the commercial power supply network, while sensors and control points are in general self-powered, for example, powered by dry or rechargeable cells.
A problem arises in such an installation as soon as the self-powered elements are of bidirectional type: how to avoid permanent listening by radio-frequency receivers, the effect of which is to increase consumption and therefore reduce autonomy.
This problem has given rise to numerous inventions.
In a first group of inventions, patent application WO 00/28776 discloses receivers that wake up at a fixed time. It is therefore necessary that they contain at least one clock device which is permanently powered. A similar procedure is described in application EP 1 404 043.
A second group of inventions uses routers, for which the power supply problem does not arise, for example because they are powered on the commercial network, or because they are powered by a large energy reserve.
Patent application EP 1 545 076 describes the use of an automobile as relay of a portable device in a cellular network. Similar uses are found in applications JP59092133 and JP11276343. In a field related to home automation, U.S. Pat. No. 6,525,645 also describes the use of a repeater situated in the automobile and powered by its accumulator. Provided that the identification code is valid, the signal sent by the portable device held by the driver is repeated identically but with a more powerful signal by the repeater.
U.S. Pat. No. 7,027,416 also describes an installation of home-automation type: the self-powered devices each communicate with a router, by means of a low power communication, making it possible to reduce both range and consumption. The routers intercommunicate at higher power and according to different frequency bands, with a different protocol from that used in the low level communication. Communication between two elements requires the use of at least one router, in general several. It is provided that a self-powered element is periodically or randomly deactivated according to a pre-established duty ratio. The router having to communicate with such an element is warned of this manner of operation and takes account thereof to define the transmission instants. It is not provided that elements can intercommunicate directly, this being explained by the hierarchized nature of the network and by the fact that the decisions are taken by a local and/or remote controller, for example via the telephone network. The controller also manages the main routing table, on the basis of knowledge of the local routing tables.
A third group of inventions describes the use of repeaters of “mailbox” type.
U.S. Pat. No. 4,803,487 deals with the case of a pager with remote display means. For example, the main receiver, or first receiver, receives the messages and stores them in memory. It is powered by a battery of high capacity, and nevertheless of an economizer device, prompting sleep over a given time interval if the pager is not the message destination. This main receiver communicates by a possibly bidirectional means with the remote display. The link between the display and the first receiver is carried out with a different protocol from the communication protocol used to transmit the messages to each pager. On activation of a user control, the transmitter of the remote display interrogates the first receiver, which then sends the information contained in memory to the receiver of the remote display.
The prior art devices therefore call upon complex structures supporting several communication means or protocols, or provide a single communication means but with limited performance for portable remote control, the problem then being dealt with from the standpoint of reducing consumption at transmission, and not at reception. A problem arises in particular when the portable remote control is replaced with a sensor that is not easily accessible (and for which it is difficult to replace cells), and still more when the intelligent relay is itself self-powered, or indeed portable.
Furthermore, application US 2006/0025181 discloses an installation comprising a set of elements communicating over a network. One of the elements can moreover communicate with a self-powered terminal that does not form part of the network. This self-powered terminal operates according to an alternating cycle of wakeup and sleep phases so as to optimize its autonomy. Thus, in the case where the element of the network wants to transmit data to the terminal while the latter is in a sleep phase, this network element must store the data in memory and wait for a self-powered terminal wakeup information before actually sending it the data. In this installation, the terminal's possibilities of communication with the elements of the network are very limited: it can only communicate, both in transmission and in reception, with a single element.